Re: Apple //e Power Supplies

["Tom Zuchowski" <tzuchow@attglobal.net>]

I dunno about a design flaw, but any electrolytic capacitor has a life
expectancy of about 10 years unless it is an expensive high-grade type.
Switching power supplies such as those used in the Apple II can generally be
expected to fail after perhaps 15 years due to electrolytic capacitor
degradation. Fortunately, they are easy to fix, all you have to do is
replace the electrolytic capacitors and it will be as good as new.

You can go to the trouble of getting exact replacements for the caps, but a
good rule of thumb is to use caps within maybe 10%-15% of the capacitance
and the same or higher voltage rating. Be aware that modern caps are a LOT
smaller physically than caps of the same rating from 20 years ago!

If the cap you mention is under-rated for its environment, then that is
indeed a design flaw, and that cap should be uprated in both temperature and
voltage ratings (to some extent it is the same thing.)

Tom Zuchowski


"Quadrajet1" <quadrajet1@aol.com> wrote in message
20010223020118.02994.00002350@ng-cs1.aol.com">news:20010223020118.02994.00002350@ng-cs1.aol.com...
>
>     Basically the power supples were made by either Dyna-Comp or Astec.
The
> longer power supplies supplied a higher current rating than did the
shorter
> ones.  I prefer the Astec power supplies any day, but the older ][+ power
> supplies had a bad design flaw that caused a cap to fail.
>
> Raymond